"The cast was completely shocked and several – Anne and Marion [Cotillard], a couple of the men – were in tears," a source tells PEOPLE. "There was enormous, enormous sadness."

While en route, Bale, who plays Batman, released a statement:

"Words cannot express the horror that I feel. I cannot begin to truly understand the pain and grief of the victims and their loved ones, but my heart goes out to them."

Dark Knight director Christopher Nolan earlier released a statement expressing "profound sorrow" for the Aurora, Colo., shooting that left 12 dead and more than 50 wounded.

"Nothing any of us can say could ever adequately express our feelings for the innocent victims of this appalling crime, but our thoughts are with them and their families," Nolan said in the statement.

Once back in the U.S., Hathaway issued a statement in addition to the one Nolan sent on behalf of the cast.

"My heart aches and breaks for the lives taken and altered by this unfathomably senseless act. I am at a loss for words how to express my sorrow. My thoughts and prayers are with the victims and their families."

Warner Brothers has also decided to withhold box office numbers for Dark Knight, saying in another statement that they will wait until Monday "out of respect for the victims and their families."